Centering device



w. w. HARTMAN Sept. 26, 1939.

CENTERING DEVICE Filed Feb. 9, 1938 p 00 0 ow a a &

Patented Sept. 26, 1939 UNITED STATES PATENT OFFICE William i s fngeles, Calif.

Application February s, 1938, Serial No. 189,674-

2 Claims. (01. 1664) My invention relates to an improved centering device, of the type using outwardly'bowed springs for centering pipe, tubing, or the like, or rods of any sort, in a hole. l

. While my means or device is of general utility wherever centering of the foregoing type is desired, nevertheless, a field of especial utility arises in centering either slotted or unslotted pipe in a gravel packed well.

In gravel packing a well the process briefly is to complete the hole with permanently installed steel casing of moderately large diameter, to a point just above the strata that is to produce the desired product, usualy oil, water or gas.

drilling then proceeds through the center of the easing into this producing strata to the desired depth, often several hundred feed, and thereafter this hole is reamed to a diameter substantially larger than the bore of the casing, along the go entire length of the' hole below the casing. It is into this reamed hole that the strainer pipe is lowered, and then sufficient coarse gravel is fed into the well to completely fill the space between ,the strainer pipe and the walls of this reamed hole.

The object of all this is that in the finished well the fluid will pass from the fine sands or other formation comprising the producing strata, thru the gravel envelope thus supplied, into the strainer pipe, from whence it' rises to the top of the.

so well. The purpose of the gravel pack is toact as a filter and hold back the fine sandsor particles in the producing strata, to thereby prevent or retard same from clogging or filling the strainer pipe or otherwise interfering with the emcient {operation of the well. But in order that the supplied envelope of gravel can properly protect the strainer pipe the latter should be centralized in the hole to insure the distribution of a uniform thickness of gravel all around the strainer 40 pipe. i

It is in the process of thus centralizing the strainer pipe, or any other pipe embedded in gravel, that my centering device finds its field of special utility.

In the process of completing a well in-the foregoing manner, it occasionally happens for various reasons, that after my centering device and the strainer pipe are immersed in the supplied gravel, it becomes necessary to pull the strainer pipe and my centering device mounted thereon,

up through the gravel into the casing, and thence on up through the well. Under these circumstances two series difllculties may be encountered with ordinary centering devices owing to the relatively wide springs which they use to procuregood bearing against the walls of the hole. These diffi'culties are, first, that such wide springs are hard to pull up through the gravel as .they offer much resistance, and, second, that at the place wherethe device passesfrom the reamed hole 5 into the smaller casing, the springs must fold inward against the pipe to accommodate themselves to the reduced casing diameter, and the gravelnaturally tends to be trapped between the ordinary wide fiat springs and the pipe, and thereby 10 obstructs the proper folding in of such springs. This trapping of the gravel occurs mostly near the collars where the wide fiat springs are close to the pipe, and where there is particularly'little room for the gravel to escape, thereby producing i this trapping of the gravel. All the foregoing makes it difilcult both to raise the device through the :gravel, and to cause it to enter the smaller casing from the reamed hole.

It is these dimculties that my improvement largely eliminates;

'Broadly speaking my invention is characterized by having springs that are relatively wide where they extend out the furthest to supply the desired bearing, and that are relatively narrow where they approach the collars, or pipe, or other tubular member on which they are mounted, to thereby permit the free escape of the gravel andaid the entry of the device from the hole into the smaller casing, and also minimize the resistance in pulling the .device upward through the gravel.

.Other features, objects and benefits of my invention will become apparent fromco'nsideration of the attached drawing, also from the following 1 detailed description, and from the claims.

The broad features of my invention may be applied and utilized in various ways, to suit various tastes and circumstances, it being understood thatin the accompanying drawing, and in the following detailed description, I am illustrating only one preferred form of my invention, and two modifications thereof, bu I am aware that still other modifications can be made without departing from the spirit of my invention, which is lim- 45 ited only by the terms of the claims. r

Infthe drawing, like parts are designated by like reference numerals.

Fig. 1 is a front elevation'showing my centering device installed in a well, the soil, producing strata'and certain parts of the well being-shown in section, to disclose mycentering device in place.

Fig. 2 is a section through the well taken along line x -X looking in the direction of the arrows, in Fig. 1.

Fig. 3 is a fragmental sectional view along line XF-X, looking in the direction of the arrows, in Fig; 1. x

Fig. 4 is a fragmental sectional view along line X X looking in the direction of the arrows,

in Fig. 1. r I

Fig. 5 is a fragmental sectional view along line x -X looldng in the direction of the arrows, in Fig; 1. i p

Fig. 6 illustrates the shape of the bearing member shown in Fig. 1, before the ends are folded under to embrace the springs.

Fig. 7 is a front elevationof a modificationbf my device, the drawing being confined to a typical fragment of the device along one spring, this being suflicient to clearly illustrate the modification.

Fig. 8 is a section along broken line x i-X looking in the direction of the arrows,., in Fig. 7,

a fragment of the pipe being also included in Fig. 8.

Fig. 9 is a front elevation of another modified form of my device.

I will first describe the preferred form of my invention, illustrated in Figs. 1 to 6, inclusive.

In Fig. 1, is seen the well casing I installed in the upper earth formation 21, and the enlarged hole 3 reamed out in the producing strata 4, below casing I. Pipe Sand strainer pipe 6, are shown installed and centralized in this enlarged hole 3, the centralizing having been accomplished by rny'device, illustrated generally by reference numeral 1, shown mounted on pipe 6, in Fig. 1.

. The supplied gravel, or gravel pack, indicated by reference numeral 8, and being in general a body of uncemented gravel-like material, completely fills hole 3 up part way into casing I, the exact height to which this gravel is carried being howcorresponding with the center line of pipe 5.

The springs I may be secured to collars 9 in any desired manner, as by flattening their ends at I I, see Fig. 1, and welding these flattened ends tothe outside of collars 9, as indicated at I2 on the central spring on lower collar 9, in Fig. 1; or the spring ends can be inserted more or less flush in notches in the collarsas will be hereinafter described in connection with mymodification shown in Figsfli and 8; or the springs can i be secured to the collars in any desired manner.

In fact in the rudimentary form of my invention shown in Fig. 9, the springs can be mounted on as will be hereinafter described.

In the preferred form of my invention, the bore of collars 9 is preferably slightly larger than pipe .6, so that the device is free to rotate on, and to have limited movement lengthwise along pipe Ii. This lengthwise movement along pipe 6, should, however, be in some way limited, becausethe length of pipe 6 may be several hundred feet, in which case it is desirable to the pipe by welding them directly onto the pipe,

have the centering device, or devices, 1, somewhat definitely located on pipe 9 according to some predetermined position or distribution.

Forthis purpose the device is more or less secured to pipe 6 in any one of various ways. This can be done forinstance, by utilizing the ordinary pipe couplings Il, which are used to join successive sections of pipe Ii together, in which case my device 'I is left free to float between any two such successive couplings I4, these butting against one or the other of my collars 9 to limit the sliding, of my device along pipe 6. Or, one 10 or the other of my collars 9, preferably the lower one, may be welded, or otherwise-secured to pipe 6, thereby leaving only the other collar 9 free to float lengthwise of the pipe to permit free flexing u of the springs, but nevertheless securing my device to pipe 6 for reasons indicated. Or in an extremely rudimentary adaptation of my invention, illustrated in Fig. 9, one or the other ends of my springs, instead of being secured to my collars 9, could obviously be secured direct to 2 the pipe, thus leaving one end of each spring free to slide lengthwise of the pipe, while the-other end is directly. secured to the pipe. The free ends'could be either entirely free, or' could be joined [to each other by using one collar,.inmanner that is obvious without additional illustration;

,But while my device can be secured to the pipe I in any of the above described ways, 'or in any other desired manner, nevertheless I prefer to limit the said lengthwise movement of my device alongthe pipe, byproviding on the pipe between my spaced apart collars 9, some sort of stop means adapted to butt against collars 9, this preferably being a ring I5, see Fig. 1, securely fastened to pipe 6, as by welding or otherwise. This mode of limiting the movement of my device on pipe 6, has the advantage that if this 'pipe, and my device, must be raised from hole 3 into casing I, the stop I5 will rise and butt 40 against my upper collar 9, and in efiect .pull all the springs 'lllupward into casing I. When the springs are pulled upward in this manner they naturally tend to fold freely inward against pipe 6, to accommodate themselves to the reduced diameter of casing lr' whereas if my springs were pushed upward from their lower ends, theywould most likely buckle or break OH, and causegeneral trouble. Also in lowering my centering device through the well-,there are circumstances inwhich it functions'nrore satisfactorily when pulled ahead by stop I5, and this therefore is my preferred mode of making the attachment. Y

As shown in Fig. 1, the general shape of my.

springs can be referred to as being bowed outwardly, by which I mean that the springs in a general way arefurther from the axis A-A at places intermediate of the collars 9, than they are near collars 9, and any shape that suits this go condition is satisfactory for my invention, the precise shape being immaterial.

I My springs III, in the preferred form of my.

invention, in order-to be sufficiently strong to properly center pipe 6, and yet to be relatively narrow in a general circumferential direction about axis A-A, are made of circular'crosssection as indicated in Figs. 3, 4 and 5. This 0 cular section, in addition to combining the desired circumferential narrowness with the de- 7 sired strength of the springs, has the further advantage -of affording excellent escape for the gravel from the pocket-like areas .I6, see Fig. 1,-

Where fip gs and pipe are close together, and where the above described trapping of the 7 1 springs.

5 vary considerably, the sole ing members are member being free to slide 35 them 55, and 8, my springs along the narrow portion gravel behind the ordinary wide springs occurs, and in addition such round springs have the advantage that they pull up much more easily than the ordinary wide -flat But in order that my springs may have good bearing against the formation 4, at the place where the bearing occurs, I provide suitable bearing members H on springs III at the places 10 where these springs extend radially furthest from place usually but not necesthe axis A-A, this sarily being about midway of the ends of the springs. The precise shape and mode of attaching these bearing members I1 to springs III can requirement being that they should be relatively wider than springs in, this width being con'sidered'in a direction generally circumferential of the device, to give the bearing action referred to.- Whether these bearfastened a, the inside or the outside of spring I0, is not particularly material, although I prefer to fasten them to, the outside. In Fig. 1 these bearing members I] are shown fastened to springs III by welding l8 applied for only a limited distance between a and. "b near the center of member H, the ends IQ of this lengthwise of springs lflbut being. nevertheless secured thereto. This latter feature can be best understood by reference to Fig. 6. showing the blank form of member 11, it being understood that in finishing this blank, its ends l9 are wrapped around spring Ill and thenwelded at 20. see Figs. 3 and 4, thus securing ends lilabout springs lll'yet leaving free to slide lengthwise thereof. In this way, springs III are left. free to bend and accommodate themselves to variations of hole diameter as they pass along, and. the bearing members I1 are also free to readily accommodatethemselves to the bending of springs of members I! can freely slide along springs I0, even though secured thereto.

From Figs. 1, 2, i and 6, especially Fig. 2, it is evident that the circumferential widtha: of

5 hearing members I1 is relatively larger than that of springs l0, (indicated by 1 Fig. 2) thereby providing the bearing action above described, combined with provision for the free escape of the gravel. In a sense members 10 and 11 can, if desired, be considered as integral/and as comprising my springs, in the preferred illustrated in Figs. 1 and 2.

In. the form of my invention shown in Figs. '1 ll'are shown as consisting of relatively flat strips that are circumferentially wide along the bearing portion II, where the springs project out furthest from pipe 6', and

.1 ,that are relatively narrow circumferentially along the spring portions that approach the collars 9',

w as indicated at 25 in Fig. 7. In this form, my springs, if desired, can be made relatively-thicker 25, see'Fig. 8, than along the relatively wider bearing equalize the spring strength by compensating for the varying width. In this form of my invention thespring ends!" are shown as set into notches 21 of the collars Q, these spring ends being welded to the collars along notches 21 as indicated at 28, thereby making the spring ends It and collars l substantially flush inside and through the gravel ll, because the ends I! form of my. invention,

portion I1, such variation in thickness being intended to .bers free to slide lengthwise the springs andbearing outside. In Fig. 8 the stop ring I5 is secured to pipe 6' between the two collars 9', in manner similar to Fig. 1, so that this stop l5f is adapted to abut against edges 28 of collars 9, as'best seenin Fig. 8.

Fig. 9 illustrates a rudimentary form of my invention, in which my springs HP are attached direct to any suitable tubular member, such as thepipe itself, 6 the spring ends 28' being directly welded to pipe 8 as indicated at 21'. :'In this form of my invention; the upper ends of springs I are preferably free to slidealong the pipe so as not to interfere with the flexing of the springs. i 7

- In the various forms of my invention, it is immaterial whether the direction of the springs, viewed generally lengthwise of the pipe, is straight as indicated by the middle spring in Fig. 1, or by.

the spring in Fig. 'l, or whether the springs are spiraled lengthwise of and slightly around the pipe; and it is also immaterial whether the said collars, and bearing members on said springs at the place where the springs are bowed outward the furthest, the width of said bearing members when measured in a direction circumferential or said device being greater than the width of saidsprings when measured in the same manner, and the length of said bearing members being for. a limited distance along the length of said springs, ing member being fastened to its spring at a place intermediate of the ends of the bearing member and having the ends of'the bearing mmber'free to slide lengthwise of its spring.

2. A pipe centering device comprising in combination, two hollow cylindrical end collars in line with and spaced apart from each other, a plurality of outwardly bowed springs fastened to said collars, and bearing members on said springs at the place where said springs are bowed outward the furthest, the width of said bearing members when measured in a direction circumferential of said device being greater than the width of said springs when measured in the same manner, and the length of said bearing members extending for a limited distance along the length of said springs, each such bearing member being fastened to its spring at a place intermediate of the ends of the bearing and the ends of said bearing members being slid-'- ably fastened to the springs to cause the bearing members to flex su 'tiallyinunisunwlththebearing member, or bearing portion of the spring,

springs but leaving the ends of the bearing memof-thespringsas 

